Comparison of Variable and Constant Loading for Mesophilic Food Waste Digestion in a Long-Term Experiment
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Biomass Group, College of Engineering, Nanjing Agricultural University, 40 Dianjiangtai Road, Nanjing 210031, China
2
Water and Environmental Engineering Group, University of Southampton, Southampton SO16 7QF, UK
3
Civil, Environmental and Architectural Engineering, University of Padua, 35131 Padua, Italy
*
Authors to whom correspondence should be addressed.
Energies 2020, 13(5), 1279; https://doi.org/10.3390/en13051279
Received: 30 January 2020
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Revised: 1 March 2020
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Accepted: 3 March 2020
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Published: 10 March 2020
(This article belongs to the Special Issue Bioenergy from Organic Waste)
Operators of commercial anaerobic digestion (AD) plants frequently note the challenge of transferring research results to an industrial setting, especially in matching well-controlled laboratory studies at a constant organic loading rate (OLR) with full-scale digesters subject to day-to-day variation in loadings. This study compared the performance of food waste digesters at fluctuating and constant OLR. In a long-term experiment over nearly three years, variable daily OLR with a range as wide as 0 to 10.0 g VS L−1 day−1 (weekly average 5.0 g VS L−1 day−1) were applied to one laboratory-scale digester, while a pair of control digesters was operated at a constant daily loading of 5.0 g VS L−1 day−1. Different schemes of trace elements (TE) supplementation were also tested to examine how they contributed to process stability. Variable loading had no adverse impact on biogas production or operational stability when 11 TE species were dosed. When TE addition was limited to cobalt and selenium, the stability of the variable-load digester was well maintained for nearly 300 days before the experiment was terminated, while the control digesters required re-supplementation with other TE species to reverse an accumulation of volatile fatty acids. This work demonstrated that variation in daily OLR across quite a wide range of applied loadings is possible with no adverse effects on methane production or stability of food waste digestion, giving confidence in the transferability of research findings. The positive effect of variable OLR on TE requirement requires further investigation considering its practical significance for AD industry.
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Keywords:
variable loading; food waste; anaerobic digestion; trace elements; cobalt; selenium; process stability
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MDPI and ACS Style
Song, H.; Zhang, Y.; Kusch-Brandt, S.; Banks, C.J. Comparison of Variable and Constant Loading for Mesophilic Food Waste Digestion in a Long-Term Experiment. Energies 2020, 13, 1279. https://doi.org/10.3390/en13051279
AMA Style
Song H, Zhang Y, Kusch-Brandt S, Banks CJ. Comparison of Variable and Constant Loading for Mesophilic Food Waste Digestion in a Long-Term Experiment. Energies. 2020; 13(5):1279. https://doi.org/10.3390/en13051279
Chicago/Turabian StyleSong, He, Yue Zhang, Sigrid Kusch-Brandt, and Charles J. Banks. 2020. "Comparison of Variable and Constant Loading for Mesophilic Food Waste Digestion in a Long-Term Experiment" Energies 13, no. 5: 1279. https://doi.org/10.3390/en13051279
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